U.S. patent application number 15/742757 was filed with the patent office on 2018-07-19 for system for providing an excitation signal to an electrochemical system and method therefor.
The applicant listed for this patent is Lithium Balance A/S. Invention is credited to Andreas Elkjaer Christensen, Rasmus Mosb.ae butted.k.
Application Number | 20180203073 15/742757 |
Document ID | / |
Family ID | 56372906 |
Filed Date | 2018-07-19 |
United States Patent
Application |
20180203073 |
Kind Code |
A1 |
Christensen; Andreas Elkjaer ;
et al. |
July 19, 2018 |
SYSTEM FOR PROVIDING AN EXCITATION SIGNAL TO AN ELECTROCHEMICAL
SYSTEM AND METHOD THEREFOR
Abstract
A vehicle system provides an excitation signal to an
electrochemical system for use in Electrochemical Impedance
Spectroscopy diagnostics. The electrochemical system is connectable
to the vehicle system and the vehicle system includes a power
stage, such as a charger, connectable to the electrochemical system
for supplying electrical energy to the electrochemical system,
and/or connectable to the electro-chemical system for withdrawing
electrical energy from the electrochemical system, and an
Excitation Generation Unit comprised by the power stage or
operatively connected to the power stage. The Excitation Generation
Unit is adapted for instructing the power stage to generate an
excitation signal for use in the Electrochemical Impedance
Spectroscopy diagnostics, and the power stage is adapted for
generating the excitation signal and supplying the excitation
signal to the electrochemical system when so instructed by the
Excitation Generation Unit. A method provides an excitation signal
to an electrochemical system using the vehicle system.
Inventors: |
Christensen; Andreas Elkjaer;
(Ishoj, DK) ; Mosb.ae butted.k; Rasmus; (Ishoj,
DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lithium Balance A/S |
Ishoj |
|
DK |
|
|
Family ID: |
56372906 |
Appl. No.: |
15/742757 |
Filed: |
July 8, 2016 |
PCT Filed: |
July 8, 2016 |
PCT NO: |
PCT/EP2016/066287 |
371 Date: |
January 8, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/26 20130101;
G01R 31/389 20190101; G01R 31/007 20130101 |
International
Class: |
G01R 31/36 20060101
G01R031/36; G01N 27/26 20060101 G01N027/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2015 |
DK |
PA 2015 00405 |
Claims
1-9. (canceled)
10. An electrochemical infrastructure system, comprising: an
electrochemical system; a vehicle having a vehicle system providing
an excitation signal to the electrochemical system for use in
Electrochemical Impedance Spectroscopy diagnostics on the
electrochemical system; the electrochemical system being
connectable to the vehicle system; the vehicle system comprising a
power stage being a charger for the electrochemical system and
connectable to the electrochemical system for supplying electrical
energy to the electrochemical system, the power stage comprising an
Excitation Generation Unit, the power stage being a part of a
vehicle drive train or power electronics connectable to the
electrochemical system; the electrochemical system further
comprising an individual Response Analyzer operable to measure an
impedance of the electrochemical system in response to the
excitation signal, the Individual Response Analyzer further being
adapted for determining diagnostics of the electrochemical system
based on the impedance; the Excitation Generation Unit being
adapted for instructing the power stage to generate the excitation
signal for use in the Electrochemical Impedance Spectroscopy
diagnostics; and the power stage being adapted for generating the
excitation signal and supplying the excitation signal to the
electrochemical system when so instructed by the Excitation
Generation Unit.
11. The electrochemical infrastructure system according to claim
10, wherein the charger is an AC to DC charger.
12. The electrochemical infrastructure system according to claim
10, wherein the charger is a DC to DC charger.
13. The electrochemical infrastructure system according to claim
10, wherein the power stage is a power inverter.
14. The electrochemical infrastructure system according to claim
10, wherein the power stage is a power converter for the
electrochemical system.
15. The electrochemical infrastructure system according to claim
10, further comprising: a System Response Analyzer for measuring
the impedance of the electrochemical system in response to the
excitation signal, the System Response Analyzer further being
adapted for determining diagnostics of the electrochemical system
based on the impedance.
16. The electrochemical infrastructure system according to claim
15, wherein the System Response Analyzer comprises the Excitation
Generation Unit.
17. The electrochemical infrastructure system according to claim
10, wherein the electrochemical system comprises a plurality of
electrochemical devices and a plurality of the Individual Response
Analyzers, each Individual Response Analyzer being associated with
a corresponding one of the plurality of electrochemical
devices.
18. The electrochemical infrastructure system according to claim
10, wherein the electrochemical system comprises or is connected to
an Electronic Control Unit, the Electronic Control Unit comprising
or being connected to the Individual Response Analyzer.
19. A method of providing an excitation signal to an
electrochemical system for use in Electrochemical Impedance
Spectroscopy diagnostics on the electrochemical system, comprising
the steps of: providing an electrochemical infrastructure system
according to claim 10; connecting an electrochemical system to the
vehicle system; instructing the power stage, by the Excitation
Generation Unit, to generate the excitation signal for use in the
Electrochemical Impedance Spectroscopy diagnostics; and generating
and supplying the excitation signal to the electrochemical system
by the power stage.
Description
[0001] The present invention pertains to the generation of
excitation signals for use in diagnostics of electrochemical
devices by means of Electrochemical Impedance Spectroscopy.
[0002] Electrochemical Impedance Spectroscopy is a technique in
which an excitation signal is applied to an electrochemical system
for eliciting a response signal from the electrochemical system.
The response signal can then be measured to obtain information,
such as diagnostic information, of the electrochemical system.
Electrochemical Impedance Spectroscopy is inter alia described in
Orazem, M. E. & Tribollet, B. Electrochemical Impedance
Spectroscopy. (John Wiley & Sons, 2008). The excitation signal
is normally a current signal or a voltage signal applied to the
terminals of the measured system, and the waveform of the
excitation signal can be sinusoidal with single or multiple
frequencies, time-domain impulses or steps.
[0003] Electrochemical Impedance Spectroscopy can be used for
diagnosis of electrochemical devices including, but not limited to,
batteries, fuel cells, capacitors, photovoltaics,
photoelectrochemical cells, electrolysis cells, see for example
Birkl, C. R. & Howey, D. a. Model identification and parameter
estimation for LiFePO 4 batteries. IET Hybrid Electr. Veh. Conf.
2013, HEVC 2013 1-6 (2013), Deng, Z. et al. Electrochemical
Impedance Spectroscopy Study of a Lithium/Sulfur Battery: Modeling
and Analysis of Capacity Fading. J. Electrochem. Soc. 160, 553-558
(2013), Jensen, S. H., Hauch, A., Knibbe, R., Jacobsen, T. &
Mogensen, M. Modeling Degradation in SOEC Impedance Spectra. J.
Electrochem. Soc. 160, F244-F250 (2013), Mosbaek, R. R., Hjelm, J.,
Barfod, R., Hogh, J., & Hendriksen, P. V. Electrochemical
Characterization and Degradation Analysis of Large SOFC Stacks by
Impedance Spectroscopy. Fuel Cells, 13(4), 605-611 (2013), Lopes,
T., Andrade, L., Ribeiro, H. A. & Mendes, A. Characterization
of photoelectrochemical cells for water splitting by
Electrochemical Impedance Spectroscopy. Int. J. Hydrogen Energy 35,
11601-11608 (2010), Taberna, P. L., Simon, P. & Fauvarque, J.
F. Electrochemical Characteristics and Impedance Spectroscopy
Studies of Carbon-Carbon Supercapacitors. J. Electrochem. Soc. 150,
A292 (2003), Leever, B. J., Bailey, C. a., Marks, T. J., Hersam, M.
C. & Durstock, M. F. In situ characterization of lifetime and
morphology in operating bulk heterojunction organic photovoltaic
devices by impedance spectroscopy. Adv. Energy Mater. 2, 120-128
(2012), and Fabreqat-Santiaqo, F. et al. Correlation between
photovoltaic performance and impedance spectroscopy of
dye-sensitized solar cells based on ionic liquids. J. Phys. Chem. C
111, 6550-6560 (2007).
[0004] The diagnostics may comprise determining various parameters
of the electrochemical system, for example as described in Buller,
S., Thele, M., Karden, E. & De Doncker, R. W. Impedance-based
non-linear dynamic battery modeling for automotive applications. J.
Power Sources 113, 422-430 (2003), Ender, M., Weber, A. &
Ivers-Tiffee, E. Analysis of Three-Electrode Setups for
AC-Impedance Measurements on Lithium-Ion Cells by FEM simulations.
J. Electrochem. Soc. 159, A128 (2012), J. Morrison, W. Morrison,
and J. Christophersen, Method of detecting system function by
measuring frequency response US Patent 20 100 274 510, (2010), Huet
F. A review of impedance measurements for determination of the
state-of-charge or state-of-health of secondary batteries. J. Power
Sources 70, 59-69 (1998), Itagaki, M., Honda, K., Hoshi, Y. &
Shitanda, I. In-situ EIS to determine impedance spectra of
lithium-ion rechargeable batteries during charge and discharge
cycle. J. Electroanal. Chem. 1-7 (2014), Jespersen, J. Capacity
measurements of Li-ion batteries using AC impedance spectroscopy.
World Electr. Veh. J. 3, (2009), Lvovich, V., Wu, J., Bennett, W.,
Demattia, B. & Miller, T. Applications of AC Impedance
Spectroscopy as Characterization and Diagnostic Tool in Li-Metal
Battery Cells. ECS Trans. 58, 1-14 (2014), and Mauracher, P. &
Karden, E. Dynamic modelling of lead/acid batteries using impedance
spectroscopy for parameter identification. J. Power Sources 67,
69-84 (1997).
[0005] The excitation signal used for Electrochemical Impedance
Spectroscopy may be implemented by different means, see R.
Robinson, System noise as a signal source for impedance
measurements on batteries connected to operating equipment. Journal
of Power Sources, vol. 42, no. 3, pp. 381-388, (1993), Howey, D.
A., Mitcheson, P. D., Yufit, V., Offer, G. J. & Brandon, N. P.
Online measurement of battery impedance using motor controller
excitation. IEEE Trans. Veh. Technol. 63, 2557-2566 (2014),
Troeltzsch, U. & Kanoun, O. C. 1-Miniaturized Impedance
Measurement System for Battery Diagnosis. Proc. Sens. 2009, Vol. I
251-256 (2009), Beer, C. De, Barendse, P., Pillay, P., Pullecks, B.
& Rengaswamy, R. Online fault diagnostics and impedance
signature mapping of High Temperature PEM fuel cells using rapid
small signal injection. Electrochim. Acta 35, 1798-1803 (1990), and
Xie, C. J., Liu, J. B. & Zhao, H. B. AC-DC Isolation of EIS
Impedance Test System for Li-Ion Battery Packs. Adv. Mater. Res.
823, 509-512 (2013).
[0006] One promising application of Electrochemical Impedance
Spectroscopy is for obtaining parameters such as State-of-Charge
(SoC) and State-of-Health (SoH) of batteries used in Electrical
Vehicles. In applications like this it is paramount to be able of
having an accurate measure of remaining charge in the batteries in
order to make an accurate prediction of remaining range for the
electrical vehicle.
[0007] The same considerations apply for nearly every conceivable
system in which energy is stored in electrochemical systems, be it
in the shape of smaller lithium-ion batteries in cell-phones or
computers, or larger batteries used for grid storage.
[0008] One drawback of Electrochemical Impedance Spectroscopy is
that the technique adds further cost and complexity to the already
high cost of the electrochemical system itself including the
therewith associated auxiliary equipment such as the Battery
Management System and other control electronics.
[0009] Thus, one on one hand wider adoption of electrochemical
systems as bearers of energy, in particular in electrical vehicles,
may be hampered by the inaccuracy in determining the state of the
electrochemical system, e.g. State-of-Charge and State-of-Health,
using techniques other than Electrochemical Impedance
Spectroscopy.
[0010] On the other hand the implementation of Electrochemical
Impedance Spectroscopy could also hinder wider adoption of for
example electric vehicles due to the increase in cost of the
electrochemical system, i.e. the batteries needed to power the
electric vehicle.
[0011] It is therefore an object of the present invention to
provide a system and a method which lower the cost and/or
complexity of diagnosis of electrochemical systems by
Electrochemical Impedance Spectroscopy.
[0012] It is a further object of the present invention to provide a
system and a method for providing excitation signals for use in
Electrochemical Impedance Spectroscopy at in a simpler way and/or
at a lower cost.
[0013] At least one of the above objects, or at least one of the
further objects which will be evident from the below description of
the present invention, is according to the first and second aspects
of the present invention achieved by a system for providing an
excitation signal to an electrochemical system as defined in claim
1 and a method of providing an excitation signal to an
electrochemical system as defined in claim 13.
[0014] By using the power stage to generate and supply the
excitation signal, when instructed to do so by the Excitation
Generation Unit, the already present power electronics comprised by
the power stage can now be used also for the generation and supply
of excitation signals, thus decreasing the cost and complexity of
obtaining diagnosis of the electrochemical system by
Electrochemical Impedance Spectroscopy. This is in contrast to
using a prior art Excitation Generation Unit in which all
components needed for generating the excitation signal are provided
in the Excitation Generation Unit and which leads to an increased
cost and complexity. In the system according to the first aspect of
the present invention some of the already present power electronics
in the power stage can now be used for the primary purpose, i.e.
supplying electrical energy to the electrochemical system or
withdrawing electrical energy therefrom, and, when needed, also for
the secondary purpose of generating and supplying the excitation
signal, thus reducing the number of components needed for the two
purposes.
[0015] Further, as the power stage and the Excitation Generation
Unit are part of the system, and not part of the electrochemical
system, the cost of the electrochemical system is decreased as each
electrochemical system can be excited for the purpose of
Electrochemical Impedance Spectroscopy diagnostics when each
electrochemical system is connected to the system.
[0016] This obviates the need of including an Excitation Generation
Unit in each electrochemical system, thus further lowering
costs.
[0017] In the case of the electrochemical system being a battery
used in an electrical vehicle, and the system being comprised by a
charging station for the electrical vehicle, the above may for
example enable a lower cost implementation of service tools, i.e.
servicing and diagnostics of the battery in the electrical vehicle,
and fleet management, as more of the existing components are used.
Further, in this case a single charging station may be used with a
plurality of electrical vehicles for facilitating Electrochemical
Impedance Spectroscopy diagnostics on a plurality of
electrochemical systems in the plurality of electrical
vehicles.
[0018] In the context of the present invention the term
electrochemical system covers both a single electrochemical device,
i.e. a single electrochemical cell or unit, and a collection of
multiple electrochemical devices, e.g. cells, connected
electrically in either series, parallel or a combination
thereof.
[0019] Electrochemical Impedance Spectroscopy (EIS) is a technique
for characterising electrochemical systems and for obtaining
diagnostics on the systems. The technique uses the injection of an
electrical signal, i.e. excitation signal, and an analysis of the
resultant response signal. The injected signal, or excitation, can
have many types of waveform, typically single- or multi-frequency
sinusoidal signals or time-domain impulses or steps are used, see
Barsoukov, E., Ryu, S. H. & Lee, H. A novel impedance
spectrometer based on carrier function Laplace-transform of the
response to arbitrary excitation. J. Electroanal. Chem. 536,
109-122 (2002). The excitation signal can either be a voltage or
current signal.
[0020] If the excitation is sufficiently small the measured
response can be used to calculate the impedance of the system. The
small excitation is mainly necessary due to the linear
approximation, but for certain electrochemical devices, the system
may also change state if the excitation is not kept sufficiently
small. Due to the time dependent nature of the excitation there
might be a phase change in the measured system and the complex
resistance, or impedance Z(.omega.), can be found from Ohms law
when written using complex notation if the voltage and current is
given by:
U(.omega.)=U.sub.0e.sup.j.omega.t and
I(.omega.)=I.sub.0e.sup.j(.omega.t-.PHI.).
[0021] From which it follows that the impedance is:
Z ( .omega. ) = U ( .omega. ) I ( .omega. ) = U 0 I 0 e j .phi.
##EQU00001## Z ( .omega. ) = Z e j .phi. = R real + j R img
##EQU00001.2##
[0022] Changing the excitation frequency of the sinusoidal input
signal results in a changed angular frequency, .omega. as
.omega.=2.pi.f. The resulting impedance spectrum, for Z(.omega.)
over the tested frequency range, can provide information on the
condition of the electrodes and be used to quantify the kinetics of
the electrochemical device.
[0023] In a system of electrochemical devices, where the devices
are interconnected in series and parallel connections, it is
possible to measure the impedance of the entire system or of each
individual unit.
[0024] The term system encompasses the term primary system.
[0025] The term electrochemical system encompasses the term
secondary electrochemical system.
[0026] The electrochemical system may comprise any of batteries,
fuel-cells, super capacitors, photo-electro-chemical-cells, and
solar cells. A plurality of different electrochemical systems may
be connectable or connected to the system simultaneously or
sequentially.
[0027] In the context of the present invention the term connectable
is to be understood as also comprising connected.
[0028] The power stage is adapted for supplying electrical energy
to the electrochemical system, e.g. when the power stage is a
charger, and/or for withdrawing electrical energy from the
electrochemical system, e.g. when the power stage is an inverter or
converter for supplying electrical energy from the electrochemical
system to a consumer of the electrical energy.
[0029] The power stage comprises power electronics such as
rectifiers, inverters, transformers, drivers, filters, etc.
combined to enable power to be moved and/or converted between
systems.
[0030] The Excitation Generation Unit (EGU) has the purpose of
directly or indirectly controlling the power stage to generate the
excitation signal. The Excitation Generation Unit may in some
embodiments be adapted for instructing the power stage to generate
the excitation signal by generating an intermediate excitation
signal which is then delivered to the power stage and then
amplified and or frequency-shifted by the power stage. In other
embodiments the Excitation Generation Unit merely provides a basic
step signal or other simple signal and the power stage generates
the excitation signal. Thus the instruction from the Excitation
Generation Unit to the power stage may be any of an intermediate
signal having the intended waveform and/or frequency, but lacking
the proper amplitude and/or frequency, to a basic step signal which
the power stage detects and the generates the excitation
signal.
[0031] The Excitation Generation Unit may be comprised by the power
stage, i.e. be a part of the power stage, or may alternatively be
connected to it as a separate unit.
[0032] The power stage may be adapted for generating the excitation
signal by comprising controllable power electronics and/or by the
power electronics comprising accessible terminals for setting
parameters, such as for example output voltage or current, of the
power electronics. Applying the signal or instruction to these
terminals may then cause the power stage to vary its output to form
the excitation signal. In the case of the power stage comprising
controllable power electronics such as the power stage is
controllable through a data bus, the Excitation Generation Unit may
instruct the power stage to operate its power electronics in such a
way as to generate the excitation signal.
[0033] The power stage may supply the excitation signal to the
electrochemical system via a main power bus which is normally used
when transferring electrical power from and/or to the
electrochemical system. Alternatively the power stage may supply
the excitation signal via a secondary power bus used only for
supplying the excitation signal.
[0034] The electrochemical system may be connected to the system
using a standard power cable or any standard connectors such as the
IEC 62196 standard.
[0035] The instructing of the power stage, by the Excitation
Generation Unit, may be deliberate as selected and initiated by a
user of the system, or may be spontaneous according to the
adaptation of the Excitation Generation Unit. The Excitation
Generation Unit may for example be adapted for instructing the
power stage to generate an excitation signal every time the
electrochemical system is connected to the system.
[0036] Typically the power stage is a charger but other variants
are possible as defined in claims 2 to 6.
[0037] Alternatively or additionally, the system itself may be a
charger, inverter or converter, or the system may be a part of a
charger, inverter or converter. The charger may be an AC to DC
charger or a DC to DC charger. The power stage may supply
electrical energy to the electrochemical system, for example where
the system is a charger such as in a charging station for en
electrical vehicle, or the power stage may withdraw electrical
power from the electrochemical system, for example where the system
is positioned onboard an electrical vehicle and the power stage is
a power converter or power inverter in the drive train of the
electrical vehicle.
[0038] By the advantageous embodiment of the system according to
the first aspect of the present invention as defined in claim 7, a
very cost effective implementation of Electrochemical Impedance
Spectroscopy diagnostics is made possible for electric vehicles.
The stationary charging station may for example be used to recharge
a number of different electric vehicles. The electrochemical system
may for example comprise one or more Lithium-ion batteries and the
electrochemical system may be connectable to the charging station
via a power cable and connector. The electrochemical system may be
integrated with or in the electric vehicle, or alternatively the
electrochemical system may be removable from the electric vehicle.
The vehicle or the mobile device should be connectable to said
stationary charging station for receiving electrical energy
therefrom. Restated differently, a further aspect of the present
invention may thus concern a stationary charging station comprising
a system according to the first aspect of the present invention for
charging a vehicle or mobile device comprising the electrochemical
system.
[0039] By the advantageous embodiment of the system according to
the first aspect of the present invention as defined in claim 8 a
very cost effective implementation of Electrochemical Impedance
Spectroscopy diagnostics is made possible for grid storage systems
and residential energy storage systems. Thus a grid storage system
comprising the system according to the first aspect of the present
invention may be connected or connectable to a number of different
electrochemical systems such as batteries, fuel-cells, super
capacitors, solar cells, etc. while all of the electrochemical
systems may be excited for Electrochemical Impedance Spectroscopy
using a single Excitation Generation Unit.
[0040] Restated differently, a further aspect of the present
invention may thus concern a grid storage system or residential
energy storage system comprising a system according to the first
aspect of the present invention.
[0041] In an alternative embodiment of the system according to the
first aspect of the present invention as defined in claim 9 the
system is comprised by a vehicle or mobile device. This may be the
case where the vehicle is designed to use transient electrochemical
systems such as replaceable batteries or electrochemical systems in
which an electrolyte is replenished after being used. Thus each set
of replaceable batteries need not comprise all components needed
for Electrochemical Impedance Spectroscopy diagnostics; rather cost
is lowered by the system being comprised by the vehicle or mobile
device.
[0042] The power stage may for example be an inverter or converter
in the vehicle drive train, or a charger connected to the
electrochemical system.
[0043] Restated differently, a further aspect of the present
invention may thus concern a vehicle or mobile device comprising a
system according to the first aspect of the present invention
wherein the power stage is a part of the vehicle or mobile device
drive train or power electronics connectable to the electrochemical
system.
[0044] In order to obtain Electrochemical Impedance Spectroscopy
diagnostics the system may further, as defined in claim 10,
comprise a System Response Analyzer connected or connectable to the
electrochemical system for measuring the response elicited by the
excitation signal. Specifically it is the impedance of the
electrochemical system which is measured by comparing the
excitation signal (often a voltage signal) and the response signal
(often a current signal). The System Response Analyzer may be
adapted for determining diagnostics by comparing the measured
impedance to previously stored impedance measurements, by directly
evaluating the impedance for example by evaluating the appearance
of a Nyquist plot of the imaginary part of the impedance vs. the
real part of the impedance, or by using a circuit model of the
electrochemical system. Parameters such as State-of-Charge (SoC),
State-of-Health (SoH) and Remaining-useful-life (RUL) may be
obtained by calculating the real and imaginary parts of the
impedance and possibly representing the Impedance in a Nyquist
plot, and then determining the SoH and/or SoC of the
electrochemical system by curve fitting of a circuit model for the
electrochemical system to the calculated real and imaginary parts
of the impedance or the Nyquist plot.
[0045] The System Response Analyzer is connected to all, if
several, electrochemical systems which are connected to the same
power stage. Thus, if several electrochemical systems are connected
to the same power stage the measured impedance, and therefore the
determined Electrochemical Impedance Spectroscopy diagnostics, is
representative for the total electrochemical systems.
[0046] In some embodiments the System further comprises a System
Control Unit. The System Control Unit may comprise the System
Response Analyzer or be connected to it for assisting in
determining the diagnostics of the electrochemical system. The
System Control Unit may for example be an already present System
Control Unit controlling charging when the system is part of a
charger.
[0047] Alternatively, or additionally, as defined in claim 9, an
Individual Response Analyzer is comprised by, or connected to, the
electrochemical system. This is advantageous as it provides for a
more detailed measurement of the response signal and therefore a
more detailed diagnostics. This is of special interest where more
than one electrochemical system, or an electrochemical system
comprising several electrochemical units, is connected or
connectable to the system.
[0048] The embodiments of claims 10 and 11 may be combined so that
both a System Response Analyzer and one or more Individual Response
Analyzers are used.
[0049] The Response Analyzer may determine the diagnostics by
itself, or alternatively an Electronic Control Unit directly
connected to the electrochemical system may work together with the
individual response analyzed for determining the diagnostics.
[0050] The Electronic Control Unit may be an already present
Battery Management System or other power electronics in or
connected to the electrochemical system.
[0051] Furthermore the Individual Response Analyzer may be
connectable to the System Control Unit (if present).
[0052] Typically the electrochemical system comprises a plurality
of electrochemical devices and a plurality of Individual Response
Analyzers as defined in claim 12 This makes it possible to
determine Electrochemical Impedance Spectroscopy diagnostics for
each individual electrochemical device and that thereby
state-of-charge and can be more accurately determined and charge
balancing of the electrochemical system may be performed more
effectively.
[0053] Generally the electrochemical system comprises or is
connected to an Electronic Control Unit. In these embodiments the
Electronic Control Unit may comprise or be connected to the
Individual Response Analyzer or the Individual Response Analyzers
as defined in claim 13. The Electronic Control Unit may assist the
Individual Response Analyzer(s) in determining the Electrochemical
Impedance Spectroscopy diagnostics.
[0054] A further aspect of the present invention concerns an
electrochemical infrastructure system as defined in claim 14.
[0055] The invention and its many advantages will be described in
more detail below with reference to the accompanying schematic
drawings, which for the purpose of illustration show some
non-limiting embodiments, and in which:
[0056] FIG. 1 shows a system and method for providing an excitation
signal to an electrochemical system according to first embodiments
of the first and second aspects of the present invention, and
[0057] FIG. 2 shows a system and method for providing an excitation
signal to an electrochemical system according to second embodiments
of the first and second aspects of the present invention.
[0058] In the below description, one or more `signs added to a
reference number indicate that the element referred to has the same
or similar function as the element designated the reference number
without the `sign, however, differing in structure.
[0059] When further embodiments of the invention are shown in the
figures, the elements which are new, in relation to earlier shown
embodiments, have new reference numbers, while elements previously
shown are referenced as stated above. Elements which are identical
in the different embodiments have been given the same reference
numerals and no further explanations of these elements will be
given.
[0060] FIG. 1 depicts a system 10 comprising a power stage 12
capable of providing AC or DC output. A main power bus 14 is
connected to the power stage 12 and the power stage 12 is further
connected to an Excitation Generation Unit (EGU) 16 via a first
data bus 18, and to the main power bus 14 via a first power bus 20.
The Excitation Generation Unit is adapted to instruct the power
stage 12, via the first data bus 18, to generate an excitation
signal on the main power bus 14, and the power stage is likewise
adapted to be able for receiving the instruction from the
Excitation Generation Unit 16 and to generate and emit the desired
excitation signal. The excitation signal can either be produced on
top of the output from the power stage 12, or as a separate
signal.
[0061] The system 10 described thus far comprises all necessary
components for providing an excitation signal to an electrochemical
system.
[0062] Thus a first electrochemical system or device 50 may as is
shown in FIG. 1 be connected to the main power bus 14 for receiving
electrical power from the power stage 12. Typically the system 10
is part of or comprised by a charger for the electrochemical system
50 such that the power stage 12 provides electrical energy to the
electrochemical system 50 via main power bus 14 for charging the
electrochemical system 50.
[0063] In order to obtain Electrochemical Impedance Spectroscopy
diagnostics for the first electrochemical system or device 50 a
Response Analyzer is needed for measuring the response signal of
the electrochemical system 50 to the excitation signal from the
Excitation Generation Unit. In the simplest implementation this
Response Analyzer is implemented by a System Response Analyzer 22
connected to the main power bus 14 via second power bus 24. The
System Response Analyzer 22 may, as shown in FIG. 1, be separate
from the Excitation Generation Unit 16, or alternatively it may be
a part of it.
[0064] The System Response Analyzer 22 measures the excitation
signal, and the response signal that is elicited by the excitation
signal from the first electrochemical system or device 50, on the
main power bus 14 and determines the impedance from the
measurements. The measured impedance may be further treated by the
System Response Analyzer 22 for determining a parameter of the
first electrochemical device or system 50, or alternatively a
System Control Unit (SCU) 26 is included in the system 10 for
determining the parameters. For this purpose the System Control
Unit 26 is connected to the System Response Analyzer 22 via a
second data bus 28. The system Control Unit 26 may have further
functions such as controlling the power stage 12 via third data bus
30, for example for controlling the charging of the first
electrochemical device or system 50, and for controlling the
Excitation Generation Unit 16 via a fourth data bus 32 for
controlling when and how the Excitation Generation Unit 16
instructs the power stage 12 to generate and send out an excitation
signal on the main power bus 14.
[0065] Although the system 10 as described so far provides a cost
effective way of obtaining Electrochemical Impedance Spectroscopy
diagnostics on a first electrochemical system or device 50
connected to the systems 10 main power bus 14, the response
measured and thus the impedance and diagnostics determined concern
only the total connected first electrochemical system or device 50.
In particular where a plurality of different electrochemical
devices or systems 50 are connected simultaneously to the main
power bus 14, or where the electrochemical device or system 50
comprises a plurality of individual units such as battery cells,
capacitors, etc, there may arise a need to determine the response
of each of these individual units separately.
[0066] This may be obtained in a cost effective way by providing,
in the first electrochemical device or system 10, or connected
thereto, Individual Response Analyzers 52, one for each
electrochemical device 50, or unit thereof. Cost is still minimized
since there is still only a single Excitation Generation Unit 16
and single power stage 12 used. Preferably, as shown in FIG. 1, in
this case the first electrochemical device or system 50 comprises
or is connected to a first Electronic Control Unit (ECU) 54 which
is connected to the first electrochemical device or system 50 and
the Individual Response Analyzer 52 via fifth and sixth data buses
56 and 58, respectively.
[0067] The Electronic Control Unit 54 may be existing hardware,
such as a battery management system, fuel cell management or super
capacitor stacks management system, or a dedicated hardware
specifically designed for acquiring the individual responses of the
electrochemical devices or systems 50 or units thereof.
[0068] Obtaining Electrochemical Impedance Spectroscopy diagnostics
for individual electrochemical devices or systems 50 may for
example be used for load balancing and charge balancing between the
individual electrochemical devices or systems 50 or units.
[0069] The individual response signal measured by the Individual
Response Analyzer 52 may be used to determine an impedance and
diagnostics by the Individual Response Analyzer 52 alone or
together with the Electronic Control Unit 54, or alternatively or
additionally the result of the diagnostics or the impedance or
other measurement is sent to the System Control Unit 26 via seventh
data bus 60.
[0070] Both System Response Analyzer 22 and Individual Response
Analyzer 52 may be used at the same time to obtain diagnostics with
different level of detail.
[0071] Some of the main advantages of the present invention are
readily apparent from studying FIG. 1. Thus, in a common
implementation the system 10 is, or is part of, a stationary
charger for an electrical vehicle. The electrical vehicle carries
the first electrochemical device or system 50 and connects to the
main power bus 14 when in need of recharging the first
electrochemical device or system 50. The System Control Unit 26 in
the system 10, or indeed the Excitation Generation Unit 16 itself
may be programmed or adapted to, before, during, or after the first
electrochemical device or system 50 has been fully charged, cause
the power stage 12 to generate and send out an excitation signal on
the main power bus 14 for obtaining a response signal from the
first electrochemical system or device 50.
[0072] Electrochemical Impedance Spectroscopy diagnostics may then
be obtained by the System Response Analyzer 22 together with the
System Control Unit 26 and presented to the driver of the
electrical vehicle carrying the first electrochemical device or
system 50 by the charger.
[0073] Alternatively or additionally the diagnostics may be
obtained by the Individual Response Analyzer 52 and presented by
the electric vehicle's Electronic Control Unit 54. The diagnostics
may be used to provide the driver of the electric vehicle with an
accurate state-of-charge, state-of-health and remaining-useful life
of the first electrochemical device or system 50 in the electric
vehicle, and may further be uploaded to a fleet manager managing a
plurality of electrical vehicles for detecting electrical vehicles
in need of a replacement first electrochemical device or system
50.
[0074] The same advantages may apply also for fuel filling stations
for fuels for electrochemical devices or systems such as fuel
cells. Thus a single Excitation Generation Unit and power stage may
be used to obtain diagnostics on fuel cells in a large fleet of
fuel cell powered vehicles.
[0075] The system 10 may also be used with stationary applications
such as for grid storage. Thus where the power stage 12 is an
inverter Electrochemical Impedance Spectroscopy diagnostics can be
obtained from a pack of electrochemical systems 50 such as super
capacitors, batteries, fuel cells or solar cells. By implementing
the Excitation Generation Unit in or connected to the inverter it
is possible to obtain diagnostics on several packs of different
types of electrochemical systems with a single Excitation
Generation Unit 16, thus saving costs.
[0076] This embodiment is shown in FIG. 2 in which first and second
different electrochemical devices or systems 50 and 50', for
example batteries, fuel cells, super capacitors or other
electrochemical devices, are connected to the main power bus 14,
the second electrochemical device or system 50' being connected via
a main power bus branch 34. Also the Electronic Control Units 54
and 54', and the Individual Response Analyzers 52 and 56' may be
different.
[0077] In the above and other embodiments of the present invention
the following parameters comprised by the diagnostics provided by
Electrochemical Impedance Spectroscopy may be determined and
monitored.
[0078] State-of-charge--Using Electrochemical Impedance
Spectroscopy the State-of-charge of batteries and super capacitors
can be estimated for better balancing of pack of cells, see Huet F.
mentioned above.
[0079] State-of-health and degradation measurement can be used to
monitor the health and degradation of electrochemical cells, see
Jensen, S. H., Hauch, A., Knibbe, R., Jacobsen, T. & Mogensen,
M., and Huet, F. mentioned above. See also Ecker, M., Nieto, N.,
Kabitz, S., Schmalstieg, J., Blanke, H., Warnecke, A., & Sauer,
D. U. Calendar and cycle life study of Li(NiMnCo)O2-based 18650
lithium-ion batteries. Journal of Power Sources, 248(C), 839-851.
(2014), and Waag, W., Kabitz, S., & Sauer, D. U. Experimental
investigation of the lithium-ion battery impedance characteristic
at various conditions and aging states and its influence on the
application. Applied Energy, 102, 885-897 (2013).
[0080] State-of-Charge, State-of-health, and other charge and
degradation parameters as well as currentvoltage characteristics
for electrochemical cells and packs can be used for fleet
management in transient systems, e.g. electrical vehicles and/or
management of an array of stationary systems.
[0081] The system 10 also allows for sophisticated current profiles
being controlled through the either the system control unit (SCU)
or EGU, e.g. as seen in Bertness, K. I. and McShane, S. J. Method
and apparatus for charging a battery. U.S. Pat. No. 6,081,098, and
Cope, R. C.; Podrazhansky, Y., The art of battery charging Battery
Conference on Applications and Advances, 233-235 (1999).
LIST OF PARTS WITH REFERENCE TO THE FIGURES
[0082] 10. System for providing an excitation signal to an
electrochemical system [0083] 12. Power stage [0084] 14. Main power
bus [0085] 16. Excitation Generation Unit (EGU) [0086] 18. First
data bus [0087] 20. First power bus [0088] 22. System Response
Analyzer (SRA) [0089] 24. Second power bus [0090] 26. System
Control Unit (SCU) [0091] 28. Second data bus [0092] 30. Third data
bus [0093] 32. Fourth data bus [0094] 34. Main power bus branch
[0095] 50. First Electrochemical Device or system [0096] 52. First
Individual Response Analyzer (IRA) [0097] 54. First Electronic
Control Unit (ECU) [0098] 56. Fifth data bus [0099] 58. Sixth data
bus [0100] 60. Seventh data bus
* * * * *